There is known a gun breech mechanism including a primer-cartridge magazine which is insertable into a wedge-type breech block. A primer-cartridge chamber is provided on a plate pivotable on the barrel, a discharge lever for the fired primer cartridge being provided therein. The actuating member of the discharge lever is disposed in the breech block. Upon travel of the breech block the plate turns and operates another actuating member which introduces a new cartridge from the cartridge-holding magazine disposed in the breech block into the primer chamber. Upon shutting of the closure device the plate is returned to its starting position. The cartridge-holding magazine is formed in the shape of a disk and is advanced stepwise whenever the closure device is opened by guiding means formed with a groove. (Earlier systems are described in German Pat. No. 1,140,491 and German Auslegeschrift 1,128,788).
There is also known a gun having a wedge-type breech block and a cartridge-holding magazine which is also disk-shaped, disposed in the breech block and advanced stepwise by means of a stepping finger during opening thereof. The magazine also serves as primer chamber during firing. In the wedge-type breech block there is also disposed a discharge lever for fired cartridges which is actuated during opening of the breech block. To ensure discharge of a cartridge and advance of the magazine in the correct order without one operation interfering with the other, the firing mechanism and an associated firing pin are disposed in a plate guided in a breech member guided along the breech block within limited guidance paths.